The presence of files within a file system hierarchy when a non-global
zone is first booted indicates that the file system data is managed by the
global zone. When the non-global zone was installed, a number of the packaging
files in the global zone were duplicated inside the zone. These files must
reside under the zonepath directly. If the files reside
under a file system created by a zone administrator on disk devices or ZFS
datasets added to the zone, packaging and patching problems could occur.

The issue with storing any of the file system data that is managed by
the global zone in a zone-local file system can be described by using ZFS
as an example. If a ZFS dataset has been delegated to a non-global zone, the
zone administrator should not use that dataset to store any of the file system
data that is managed by the global zone. The configuration could not be patched
or upgraded correctly.

For example, a ZFS delegated dataset should not be used as a /var file
system. The Solaris operating system delivers core packages that install components
into /var. These packages have to access /var when
they are upgraded or patched, which is not possible if /var is
mounted on a delegated ZFS dataset.

File system mounts under parts of the hierarchy controlled by the global
zone are supported. For example, if an empty /usr/local directory
exists in the global zone, the zone administrator can mount other contents
under that directory.

You can use a delegated ZFS dataset for file systems that do not need
to be accessed during patching or upgrade, such as /export in
the non-global zone.